Assessment of the Impact of Land Use Land Cover Changes on the Streamflow of the Woybo River Catchment, Southern Ethiopia

ABSTRACT This study investigates the impact of land use and land cover (LULC) changes on the hydrology of the Woybo River catchment, relating to sustainable water resources management policy. Landsat images were categorized into different classes using the maximum likelihood algorithm of supervised classification. The Soil and Water Assessment Tool (SWAT) model evaluated the hydrology of LULC changes, with accuracy analysis using the confusion matrix and kappa index. Sub‐basin surface runoff was analyzed using ArcGIS 10.3. Model calibration and validation were performed using the SUFI algorithm in SWAT‐CUP for 1999–2009 and 2010–2015, respectively, with monthly flow data. Results were evaluated in light of Ethiopian water policy. From 1992 to 2013, agricultural land and settlements increased from 24.5% to 41% and from 1.02% to 3.2%, respectively. Forests and grasslands decreased from 25.4% to 6.7% and from 15.1% to 5.5%, respectively. Land cover maps from 1992, 2000, and 2013 had accuracies of 87.8%, 80.8%, and 90.5%, with kappa coefficients of 0.88, 0.8, and 0.9, indicating strong classification performance. Model performance was also robust, with R 2 , NSE, and PBIAS values of 0.76%, 0.75%, and 1.8% for calibration, and 0.75%, 0.74%, and −1.5% for validation. The catchment's surface runoff increased by 7.4% from 1992 to 2000 and by 10.5% from 2000 to 2013. Increased surface runoff can impact soil water content, groundwater flow, and inter‐flow, causing harmful environmental effects. The dynamic changes in LULC, which significantly influence streamflow patterns, have not been effectively managed in alignment with Ethiopia's land use and water resources management policies, leading to challenges. Additionally, the absence of an integrated LULC and sustainable water resources management strategy has exacerbated this issue. Timely evaluation of the integrated water resource policy is crucial for ensuring sustainable water management and long‐term resource preservation.